Generally, a fan is installed in a home, a factory, or the like, and is used for discharging hazy air inside of the room to provide ventilation. The fan may be classified into a ventilation fan and a cooling fan for preventing heating an engine of an automobile or a driving part of a computer.
Meanwhile, the above-described conventional ventilation fan obtains a rotational power by a motor provided in a central portion thereof as a ventilation fan disclosed in Korean Utility Model Registration Application No. 20-1999-0001707 and a cooling fan disclosed in Korean Patent Registration No. 10-0956358. A motor shaft of the fan has wings formed in a radial shape, such that when the motor is driven, air is sucked and discharged through the rotation of the wings to perform ventilation and cooling.
However, the conventional fan as described above should have a structure in which the wings rotate by receiving the rotational power of the motor located in the central portion thereof. Therefore, when the wings rotate at a high speed, a “wind barrier” phenomenon in which wind resistance is applied to wings and the motor occurs, and smooth flow of the air is obstructed. Thereby, a significant amount of power is consumed to forcibly drive the wings. In particular, there are problems that a considerable level of noise is generated due to the forcibly driving, and a rotational efficiency is considerably reduced.